crypto/crypto_null.c

   1 /*
   2  * Cryptographic API.
   3  *
   4  * Null algorithms, aka Much Ado About Nothing.
   5  *
   6  * These are needed for IPsec, and may be useful in general for
   7  * testing & debugging.
   8  *
   9  * The null cipher is compliant with RFC2410.
  10  *
  11  * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
  12  *
  13  * This program is free software; you can redistribute it and/or modify
  14  * it under the terms of the GNU General Public License as published by
  15  * the Free Software Foundation; either version 2 of the License, or
  16  * (at your option) any later version.
  17  *
  18  */
  19
  20 #include <crypto/null.h>
  21 #include <crypto/internal/hash.h>
  22 #include <crypto/internal/skcipher.h>
  23 #include <linux/init.h>
  24 #include <linux/module.h>
  25 #include <linux/mm.h>
  26 #include <linux/string.h>
  27
  28 static DEFINE_MUTEX(crypto_default_null_skcipher_lock);
  29 static struct crypto_skcipher *crypto_default_null_skcipher;
  30 static int crypto_default_null_skcipher_refcnt;
  31
  32 static int null_compress(struct crypto_tfm *tfm, const u8 *src,
  33                          unsigned int slen, u8 *dst, unsigned int *dlen)
  34 {
  35         if (slen > *dlen)
  36                 return -EINVAL;
  37         memcpy(dst, src, slen);
  38         *dlen = slen;
  39         return 0;
  40 }
  41
  42 static int null_init(struct shash_desc *desc)
  43 {
  44         return 0;
  45 }
  46
  47 static int null_update(struct shash_desc *desc, const u8 *data,
  48                        unsigned int len)
  49 {
  50         return 0;
  51 }
  52
  53 static int null_final(struct shash_desc *desc, u8 *out)
  54 {
  55         return 0;
  56 }
  57
  58 static int null_digest(struct shash_desc *desc, const u8 *data,
  59                        unsigned int len, u8 *out)
  60 {
  61         return 0;
  62 }
  63
  64 static int null_hash_setkey(struct crypto_shash *tfm, const u8 *key,
  65                             unsigned int keylen)
  66 { return 0; }
  67
  68 static int null_setkey(struct crypto_tfm *tfm, const u8 *key,
  69                        unsigned int keylen)
  70 { return 0; }
  71
  72 static void null_crypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
  73 {
  74         memcpy(dst, src, NULL_BLOCK_SIZE);
  75 }
  76
  77 static int skcipher_null_crypt(struct blkcipher_desc *desc,
  78                                struct scatterlist *dst,
  79                                struct scatterlist *src, unsigned int nbytes)
  80 {
  81         struct blkcipher_walk walk;
  82         int err;
  83
  84         blkcipher_walk_init(&walk, dst, src, nbytes);
  85         err = blkcipher_walk_virt(desc, &walk);
  86
  87         while (walk.nbytes) {
  88                 if (walk.src.virt.addr != walk.dst.virt.addr)
  89                         memcpy(walk.dst.virt.addr, walk.src.virt.addr,
  90                                walk.nbytes);
  91                 err = blkcipher_walk_done(desc, &walk, 0);
  92         }
  93
  94         return err;
  95 }
  96
  97 static struct shash_alg digest_null = {
  98         .digestsize             =       NULL_DIGEST_SIZE,
  99         .setkey                 =       null_hash_setkey,
 100         .init                   =       null_init,
 101         .update                 =       null_update,
 102         .finup                  =       null_digest,
 103         .digest                 =       null_digest,
 104         .final                  =       null_final,
 105         .base                   =       {
 106                 .cra_name               =       "digest_null",
 107                 .cra_flags              =       CRYPTO_ALG_TYPE_SHASH,
 108                 .cra_blocksize          =       NULL_BLOCK_SIZE,
 109                 .cra_module             =       THIS_MODULE,
 110         }
 111 };
 112
 113 static struct crypto_alg null_algs[3] = { {
 114         .cra_name               =       "cipher_null",
 115         .cra_flags              =       CRYPTO_ALG_TYPE_CIPHER,
 116         .cra_blocksize          =       NULL_BLOCK_SIZE,
 117         .cra_ctxsize            =       0,
 118         .cra_module             =       THIS_MODULE,
 119         .cra_u                  =       { .cipher = {
 120         .cia_min_keysize        =       NULL_KEY_SIZE,
 121         .cia_max_keysize        =       NULL_KEY_SIZE,
 122         .cia_setkey             =       null_setkey,
 123         .cia_encrypt            =       null_crypt,
 124         .cia_decrypt            =       null_crypt } }
 125 }, {
 126         .cra_name               =       "ecb(cipher_null)",
 127         .cra_driver_name        =       "ecb-cipher_null",
 128         .cra_priority           =       100,
 129         .cra_flags              =       CRYPTO_ALG_TYPE_BLKCIPHER,
 130         .cra_blocksize          =       NULL_BLOCK_SIZE,
 131         .cra_type               =       &crypto_blkcipher_type,
 132         .cra_ctxsize            =       0,
 133         .cra_module             =       THIS_MODULE,
 134         .cra_u                  =       { .blkcipher = {
 135         .min_keysize            =       NULL_KEY_SIZE,
 136         .max_keysize            =       NULL_KEY_SIZE,
 137         .ivsize                 =       NULL_IV_SIZE,
 138         .setkey                 =       null_setkey,
 139         .encrypt                =       skcipher_null_crypt,
 140         .decrypt                =       skcipher_null_crypt } }
 141 }, {
 142         .cra_name               =       "compress_null",
 143         .cra_flags              =       CRYPTO_ALG_TYPE_COMPRESS,
 144         .cra_blocksize          =       NULL_BLOCK_SIZE,
 145         .cra_ctxsize            =       0,
 146         .cra_module             =       THIS_MODULE,
 147         .cra_u                  =       { .compress = {
 148         .coa_compress           =       null_compress,
 149         .coa_decompress         =       null_compress } }
 150 } };
 151
 152 MODULE_ALIAS_CRYPTO("compress_null");
 153 MODULE_ALIAS_CRYPTO("digest_null");
 154 MODULE_ALIAS_CRYPTO("cipher_null");
 155
 156 struct crypto_skcipher *crypto_get_default_null_skcipher(void)
 157 {
 158         struct crypto_skcipher *tfm;
 159
 160         mutex_lock(&crypto_default_null_skcipher_lock);
 161         tfm = crypto_default_null_skcipher;
 162
 163         if (!tfm) {
 164                 tfm = crypto_alloc_skcipher("ecb(cipher_null)",
 165                                             0, CRYPTO_ALG_ASYNC);
 166                 if (IS_ERR(tfm))
 167                         goto unlock;
 168
 169                 crypto_default_null_skcipher = tfm;
 170         }
 171
 172         crypto_default_null_skcipher_refcnt++;
 173
 174 unlock:
 175         mutex_unlock(&crypto_default_null_skcipher_lock);
 176
 177         return tfm;
 178 }
 179 EXPORT_SYMBOL_GPL(crypto_get_default_null_skcipher);
 180
 181 void crypto_put_default_null_skcipher(void)
 182 {
 183         mutex_lock(&crypto_default_null_skcipher_lock);
 184         if (!--crypto_default_null_skcipher_refcnt) {
 185                 crypto_free_skcipher(crypto_default_null_skcipher);
 186                 crypto_default_null_skcipher = NULL;
 187         }
 188         mutex_unlock(&crypto_default_null_skcipher_lock);
 189 }
 190 EXPORT_SYMBOL_GPL(crypto_put_default_null_skcipher);
 191
 192 static int __init crypto_null_mod_init(void)
 193 {
 194         int ret = 0;
 195
 196         ret = crypto_register_algs(null_algs, ARRAY_SIZE(null_algs));
 197         if (ret < 0)
 198                 goto out;
 199
 200         ret = crypto_register_shash(&digest_null);
 201         if (ret < 0)
 202                 goto out_unregister_algs;
 203
 204         return 0;
 205
 206 out_unregister_algs:
 207         crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));
 208 out:
 209         return ret;
 210 }
 211
 212 static void __exit crypto_null_mod_fini(void)
 213 {
 214         crypto_unregister_shash(&digest_null);
 215         crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));
 216 }
 217
 218 module_init(crypto_null_mod_init);
 219 module_exit(crypto_null_mod_fini);
 220
 221 MODULE_LICENSE("GPL");
 222 MODULE_DESCRIPTION("Null Cryptographic Algorithms");